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Channel Filtering Generates Multifractal Solute Signals
Author(s) -
Hensley Robert T.,
Cohen Matthew J.,
Jawitz James W.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079864
Subject(s) - multifractal system , scaling , channel (broadcasting) , sampling (signal processing) , streams , environmental science , scale (ratio) , streamflow , filter (signal processing) , hydrology (agriculture) , geology , physics , drainage basin , mathematics , computer science , telecommunications , geometry , fractal , quantum mechanics , mathematical analysis , computer network , cartography , geotechnical engineering , computer vision , geography
Catchments act as a sequence of hierarchical filters, damping input signals and generating less variable streamflow and stream solute concentration output signals. Spectral analysis across a wide array of solutes and catchments has revealed ~1/ f scaling behavior (i.e., spectral power inversely proportional to frequency) spanning periods of hours to decades, attributed to hillslope filtering. We hypothesize that additional filtering by stream channel processes should occur. However, most catchments in which solute scaling behavior has been resolved have channel travel times too short for this to be evident from the relatively low sampling rates utilized. We use high‐frequency (1–4 hr −1 ) sampling in larger catchments (up to 3 × 10 6 km 2 ) to show that solute signals are indeed multifractal, steepening from ~1/ f spectral at low frequencies to ~1/ f 2 at higher frequencies. Across conservative, reactive, and gaseous solutes we demonstrate that departure from 1/ f scaling occurs at frequencies that correspond with metrics of catchment size.